AlMCM-48介孔分子筛的合成研究

中国科学院山西煤炭化学研究所

Encapsulation and luminescence of the nanostructured supramolecular material [Eu(Phen)(4)](NO3)(3)/(CH3)(3)Si-MCM-41

The nanostructured material (NSM) of pure silica MCM-41 molecular sieve was synthesized with tetraethyl orthosilicate (TEOS) as the source of silica and cetyltrimethylammonium bromide (CTMABr) as the template under supersonic wave condition. Then NSM of (CH3)(3)Si-MCM-41 was obtained by introducing trimethylsilyl to MCM-41. (CH3)(3)Si-MCM-41 showed the similar TEM and XRD photographs with the normal crystal of MCM-41 and the diameter of the NSM crystallites with a hexagon shape is of about 10-40 nm. The dispersivity of (CH3)(3)Si-MCM-41 prevails over the NSM of MCM-41 as its hydrophobicity. The fluorescent intensity of (CH3)(3)Si-MCM-41 is 3.4 times as that of the MCM-41. The luminescent functional supramolecular nanostructured material was prepared in EtOH, and characterized by TEM, HRTEM, XRD, TG, IR, and elemental analysis. The results showed that the [Eu(Phen)(4)](NO3)(3) had entered into the channels of nanosized mesoporous sieve of (CH3)(3)Si-MCM-41, forming discrete centers of luminescence. The energy transferring of the host to guest, superficial effect of NSM, quanta tunnel effect, and discrete luminescent center result in the fluorescent intensity of the supramolecule enhancement.

Phenanthroline-functionalized MCM-41 doped with europium ions

Organo-functionalized MCM-41 containing non-covalently linked 1,10-phenanthroline (denoted as Phen-MCM-41) was synthesized by template-directed co-condensation of tetraethoxysilane and the modified phenanthroline (denoted as Phen-Si). XRD, FTIR, UV/VIS spectroscopy as well as luminescence spectroscopy were employed to characterize Phen-MCM-41. No disintegration or loss of the Phen-Si during the solvent extraction procedure could be observed. When monitored by the ligand absorption wavelength (272 nm), the undoped MCM-41 produces a broad band emission centered at 450 run, whereas europium (III) doped Phen-MCM-41 displays the emission of the Eu3+, i.e., D-5(0) --> F-7(J) (J = 0, 1, 2, 3, 4) transition lines due to the energy transfer from the ligands to Eu3+ as well as a broad band emission centered at 442 nm.

A transparent thin film with hexagonal mesostructure containing rhodamine 6G

A transparent thin film was prepared by depositing the sol-get mixture for the synthesis of MCM-41 mesoporous molecular sieve doped with rhodamine 6G (R6G) dye on glass substrates. The film of silica-surfactant-R6G materials, which was identified to possess hexagonally ordered mesostructure, was composed of nanocrystallites about 35 nm in diameter and 1-10 mum in thickness. Cleanness of the substrates, concentration of the sol-gel mixture and rate of evaporation of the solvent were the key factors affecting transparency and homogeneity of the film. Moreover, optical change and lack in dye aggregation were observed to the R6G-functionalized MCM-41 thin film in contrast with that in ethanol solution.

M-HMS的合成、表征及在苯酚羟化反应中的催化性能

以同晶取代方法合成了 M-HMS(M=Fe、Cu、Co、V,HMS:Hexagonal Mesoporous Silicates)中孔分子筛 .经 XRD、IR、ESP表征 ,证明过渡金属离子已进入 HMS骨架中 .在苯酚羟化反应中考察了 M-HMS的催化性能 .结果表明 ,M-HMS的催化性能明显高于相对应的 M/Si O2 负载型催化剂 .依据引入 HMS骨架的过渡金属离子是苯酚羟化反应的活性中心 ,以及 H+ 和 OH- 可能参与反应的结果提出了可能的反应机理

Covalent grafting of luminescent rare earth complex onto MCM-41 by postsynthesis

New luminescent hybrid mesoporous material was prepared by covalent anchoring rare earth complex onto MCM-41 by a postsynthesis approach. The monomer (referred to here as PABI) which plays double roles, i.e., as a ligand for lanthanide ion and as an organic functional molecule to modify MCM-41 is synthesized and characterized by H-1 NMR and MS. The fluorescence spectra show clearly that the hybrid mesoporous material possesses excellent luminescence characteristics. The hybrid mesoporous material retains the structure of MCM-41 after modification.

Preparation, characterization and luminescent properties of MCM-41 type materials impregnated with rare earth complex

Hybrid materials incorporating Eu-(TTA)(3). 2H(2)O (7hereafter designated as Eu-TTA, with TTA: thenoyltrifluoroacetone) in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES) were prepared by impregnation method. The obtained materials were characterized using X-ray diffraction (XRD), IR and diffuse reflectance spectroscopy and luminescence spectra. All the hybrid samples exhibited the characteristic emission bands of EU3+ under UV light excitation at room temperature, and the excitation spectra showed significant blue-shifts compared to the pure rare-earth complex. Although the red emission intensity in the modified hybrid was almost the half of the red emission intensity in the pure Eu-TTA complex at room temperature, the hybrid showed a much higher thermal stability due to the shielding character of the MCM-41 host.

Isobutane/butene alkylation over supported heteropoly acid catalysts: I. Influence of the structure of silica

Catalysts consisting of heteropoly acids (HPAs) supported on different silica and mesoporous molecular sieves have been prepared by impregnation and the sol-gel method, respectively, and their catalytic behavior in fixed-bed alkylation of isobutane with butene has been investigated. The activity, selectivity and stability of the supported-HPA catalysts could be correlated with the surface acidity of the catalysts, the structure of supports as well as the time on stream (TOS). In the fixed-bed reactor, the acidity of the heteropoly acid is favorable to the formation of dimerization products (C-8(=)); especially, the pore size of supports was seen to have an important effect on activity and product distribution of the catalysts. Contrary to the traditional solid-acid catalysts, the supported-HPA catalysts own an excellent stability for alkylation, which makes it possible for these supported catalysts to replace the liquid-acid catalysts used in industry.

Hydroxylation of phenol by iron(II)-phenanthroline(Phen) MCM-41 zeolite

MCM-41 mesoporous molecular sieve and iron(II)-Phen/MCM-41 have been prepared and characterized by XRD, IR, NH3-TPD, BET and UV-Vis. The iron(II)-Phen/MCM-41 molecular sieve + 30% H2O2 system is capable of performing hydroxylation of phenol.

Synthesis and characterization of manganese-modified MCM-41

Manganese-modified mesoporous MCM-41 molecular sieves were synthesized at the absence of alkaline metal ions under mild alkaline condition using cetylpyridinium bromide surfactant as a template, and characterized with X-ray diffraction, N-2 adsorption, transmission electron microscopy, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) spectroscopies. The synthesized MnMCM-41 has a high pore volume of 1.30 cm(3) g(-1) with a corresponding surface area of 1510 m(2) g(-1). The ESR and Si-29 MAS NMR spectra revealed the presence of framework manganese ions in either the as-synthesized or calcined forms. (C) 2002 Elsevier Science B.V. All rights reserved.